The 2018 Dodge Challenger SRT Demon is less than a week out from its big debut in the Big Apple, and today Dodge has dropped the final bit of info in its long-drawn-out teaser campaign for the car.

It concerns the car’s fuel system. Here, too, will be another production car first: a fuel system designed to run on 100+ high-octane fuel normally reserved for race and dedicated track cars. The high-octane fuel can already be found at many major gas stations but if you prefer regular 91-octane fuel, a button on the dash lets you swap between the two.

Note, the dash switch plus a new powertrain control module (PCM) calibrated for the high-octane fuel need to be installed after delivery. They’re included in the Demon’s crate of go-fast goodies.

The benefit of high-octane fuel is that the engine can run at a higher potency by pumping in more (there’s two fuel pumps in the Demon instead of one in the Hellcat), better burning fuel without the fear of detonation, commonly referred to as engine knock. This is when the air and fuel mix ignites before the piston is fully extended. The Demon is also upgraded with larger fuel injectors using higher rail pressure.

Dodge tells us the high-octane fuel will be required to hit the car’s maximum power rating, estimated to be well over the 707-horsepower rating of the Hellcat.

Mixing high-octane and regular fuel in the tank won’t hurt the Demon’s supercharged 6.2-liter V-8, but the high-octane function won’t activate if the combined fuel octane is too low. Should the octane level drop while on the move, a message in the instrument cluster tells the driver the car will use regular until the engine is shut off and restarted. How does the car know? The PCM monitors the engine knock sensors.

A bonus video will be released tomorrow before Dodge reveals the Demon on Tuesday, April 11. The car makes its formal debut the following day at the 2017 New York auto show.

You can view all of our past coverage on the Demon at this link. You can also visit the website to view a countdown to the live reveal of the car. And for more coverage on the N.Y. auto show, head to our dedicated hub.